JPH0223829Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention reciprocates a piston by rotating a swash plate disposed in a crank chamber, and changes the angle of the swash plate to increase capacity. The present invention relates to a variable displacement compressor, and particularly to prevention of shock or abnormally high pressure that occurs during startup.

[Prior art and its problems]

In a compressor that reciprocates a piston by rotating a swash plate arranged in the crank chamber so that it can be tilted, the pressure in the crank chamber is adjusted, and the pressure generated on the back of the piston is controlled to move the main shaft of the swash plate. A variable capacity compressor of a type in which the stroke of a piston is increased or decreased by changing the angle of inclination is known, for example, from Japanese Patent Application Laid-Open No. 158382/1982 and others.

However, in this type of compressor, the inclination angle of the swash plate is unstable when the compressor is stopped or started, and can take various inclination angles. Therefore, when such a compressor is turned on by turning on the starting switch of the automobile air conditioner and turning on the clutch, the swash plate starts with the maximum angle of inclination, that is, the compression capacity of the compressor is at its maximum. is often the case. In this case, the shock at the time of starting the compressor is large, and if the refrigerant is sucked in a liquid state, the liquid will be compressed at its maximum capacity. Therefore, there is a risk of abnormalities in internal parts, such as damage to the rocking plate rotation prevention mechanism or damage to sealing parts due to abnormally high pressure.

As a means to avoid such risks, US Pat. No. 4,543,043 discloses the following means.
The first means uses a spring to bias the swash plate to the minimum tilt angle, and the second means biases the swash plate from both sides with different springs, so that the swash plate is held at a predetermined position in a stationary state. This is to maintain the angle of .

However, in the first method, since the swash plate is held at the minimum angle by the spring when the compressor is stopped, there is a pressure difference between the crank chamber and the suction chamber to increase the swash plate inclination angle when the compressor is started. It takes a long time to obtain. Further, in some cases, the capacity of the crank chamber is so small that the above-mentioned difference in means does not occur, and there is a problem that it is impossible to change from the minimum capacity state. In the second method, the swash plate can be set at a predetermined angle when the swash plate is stopped, so the above-mentioned problem does not occur. Since the swash plate is always biased by a spring, there are problems such as abnormal vibrations of the swash plate at this natural frequency. Furthermore, since the swash plate compresses the spring near the minimum angle of inclination, the pressure in the crank chamber is required to compress the spring. As a result, the pressure applied to the piston rod and the joint increases, causing problems in the durability of the joint, and the means for introducing gas pressure to create a high pressure difference tends to become complicated.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a variable capacity compressor that can reliably maintain the angular position of the swash plate at a predetermined angle smaller than the maximum inclination angle when the compressor is stopped using a simple configuration.

[Means for solving problems]

The present invention provides a crank chamber, a main shaft disposed in the crank chamber, a swash plate coupled to the main shaft in a relationship that rotates with the rotation of the main shaft and whose inclination angle can be changed with respect to the main shaft, and a swash plate that is slidably coupled to the swash plate. a oscillating plate that oscillates in the axial direction of the rotating main shaft due to rotation of the swash plate; a piston coupled to the oscillating plate that reciprocates within a cylinder provided in the crank chamber;
A suction chamber and a discharge chamber are connected to the cylinder so that fluid is sucked into the cylinder by the reciprocating motion of the piston, compressed, and discharged from the cylinder, and the pressure in the crank chamber is adjusted. In a variable capacity compressor comprising a pressure adjusting means for controlling an inclination angle and changing a discharge volume of the fluid, the swash plate is biased in a direction in which the inclination angle is smaller than a maximum value, and the swash plate is The variable capacity compressor is characterized in that a spring means is provided that does not produce a biasing force on the swash plate in a range from a predetermined angle to a minimum angle.

Further, in an embodiment of the present invention, the spring means is constituted by a coil spring fitted into the main shaft, the natural length L of which is compressed by the back surface of the swash plate when the swash plate is at its maximum inclination, but when the swash plate is at its minimum inclination, the spring means is a coil spring fitted into the main shaft. It is set at a position and length that is not compressed by the back surface of the swash plate.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a variable displacement compressor according to the present invention.

A cylinder block 2 having a cylinder bore 2a is provided at one end of the cylinder casing 1. In the opening at the other end of the cylinder casing 1, a front housing 5 is arranged and fixed, in which a bearing 4 for bearing a main shaft 3 is press-fitted in the center.

A crank chamber 1a is formed between the inner wall of the front housing 5 and one end surface of the cylinder block 2. A rotor 6 is press-fit onto the main shaft 3 in the crank chamber 1a and rotates together with the main shaft 3. A thrust needle bearing 7 is sandwiched between one end surface of the rotor 6 and the inner wall of the front housing 5, and rotatably supports the rotor 6. Rotor 6
has an arm portion 6a projecting obliquely with respect to the main shaft 3, and a pin 6b is further implanted at the end of this arm portion 6a. Furthermore, a swash plate 8 is rotatably fitted onto the main shaft 3 in the crank chamber 1a through a loose fitting hole 8a formed in the center thereof.
An ear portion 8b is fixed to the peripheral edge of one end surface of the swash plate 8,
Furthermore, the arm portion 6a of the rotor 6 is attached to the ear portion 8b.
A long hole 8c is formed through which the pin 6b implanted in the hole 8c passes. This pin 6b is slidably passed through the elongated hole 8c, and the rotor 6 and the swash plate 8 are hingedly connected by this pin 6b. On the other hand, an annular rocking plate 9 is coaxially fitted to the swash plate 8, and a thrust needle bearing 10,
11 are held in between, and the rotation of the swash plate 8 is received by the swing plate 9. A protrusion 8d is provided on a part of the periphery of the rocking plate 9 toward the side wall of the cylinder casing 1. is slidably engaged with. This slide groove 1b is for preventing the rotation of the swing plate 9 with respect to the rotation of the swash plate 8.

Further, one end of a piston rod 12 is rotatably supported on one surface of the rocking plate 8 on the opposite side in the diametrical direction to the projection 8d, and the other end of the piston rod 12 is connected to a piston 13 disposed in the cylinder bore 2a.
is connected to.

A suction hole 14 for sucking in fluid and a discharge hole 15 for discharging fluid are bored in one end surface of the cylinder bore 2a. Connected to the cylinder block 2 is a valve plate 16 to which a discharge valve (not shown) is connected. The cylinder head 17 has a suction chamber 18 and a discharge chamber 19 separated by a partition wall 17a.
It is fixed to the cylinder block 2 with a bolt 20 via a valve plate 16.

Furthermore, a first through hole 5 is provided in the cylinder block 2 to communicate the suction chamber 18 and the crank chamber 1a.
0, a chamber 51 and a second through hole 52 are bored,
Inside the chamber 51 is a retractable pressure sensing means 2 such as a bellows.
2b and a valve portion 22a connected to the tip thereof.

Then, the pressure sensing means 22b senses the crank chamber pressure introduced through the first through hole 50, so that the valve portion 22a controls opening and closing of the second through hole 52. Therefore, from the suction chamber 18 to the first through hole 50 and the chamber 5
1. The fluid passageway leading to the crank chamber 1a via the second through hole 52 is controlled to communicate in accordance with the crank chamber pressure.

A spring 23 is press-fitted into the main shaft of the swash plate 8 between the rear rotor 6. The natural length L of the spring 23 is selected to be smaller than the maximum value of the shortest distance S between the end surface of the rotor 6 on the swash plate 8 side and the back surface of the swash plate 8. The distance S changes in accordance with the inclination angle of the swash plate 8 with respect to the main axis 3, and when the inclination angle is the maximum, S is the minimum, and when the inclination angle is the minimum, S is the maximum.
When the maximum value of S is S _nax , L is selected so that the relationship between S _nax and L is S _nax −L=ΔS.

Note that the inner diameter of the coil spring 23 is formed to be slightly smaller than the outer diameter of the main shaft 3, and is fixed onto the main shaft 3 by being press-fitted into the main shaft 3. Also, the second
The figure shows only a portion of the coil spring in the longitudinal direction.
The inner diameter is made smaller than the outer diameter of the main shaft 3 to achieve the same purpose.

In FIG. 1, a pulley 24 (not shown) for transmitting engine rotation via a belt is coaxially installed on the outside of the front housing 5 of the main shaft 3 via a bearing 25. The rotation of this pulley 24 is normally not transmitted to the main shaft 3 by the bearing 25, but when the electromagnetic coil 26 is excited, the armature 27 fixed to the end of the main shaft 3 is attracted to the rotor 29 side, and the rotation of the pulley 24 is transmitted. It is transmitted to the main shaft 3.

The operation of the variable capacity compressor configured as above will be explained.

By excitation of the electromagnetic coil 26, the armature 2
7 is attracted to the rotor 29 and rotational motion is applied to the main shaft 3 from an engine or the like, the rotational motion is transmitted to the rotor 6 fitted to the main shaft 3. This rotational motion is further transmitted to the swash plate 8, and the bearings 10,1
1 and the rotation prevention mechanism 8d-1b, the rotational motion is converted into a swinging motion of the swinging plate 9.

When the swing plate 9 swings, the piston 13 reciprocates within the cylinder bore 2a via the piston rod 12 connected thereto. The reciprocating movement of the piston 13 draws fluid from the suction chamber into the cylinder bore 2a, compresses it, and discharges it into the discharge chamber 19.

Further details of the operation during capacity control are as follows.

When the crank chamber pressure is high and the pressure sensing means 22b contracts to open the second passage hole 52, the suction chamber 18 and the crank chamber 1a are brought into communication, so the pressures in the suction chamber 18 and the crank chamber 1a are equal. Become. At this time, the stroke of the piston 13 becomes maximum (maximum compression capacity), in other words, the main shaft 3 of the swash plate 8
The angle of inclination is adjusted to be maximum. Therefore, the shortest distance S between the end surface of the rotor 6 and the back surface of the swash plate 8 becomes the minimum. Then, the end of the coil spring 23 on the swash plate 8 side contacts the back surface of the swash plate 8, and applies the repulsive force of the spring 23 to the swash plate 8.
However, since the repulsive force is generated in the maximum compression capacity range, it is operationally stable and no abnormal vibration occurs in the swash plate 8.

On the other hand, when the crank chamber pressure is low and the pressure sensing means 22b extends and the second passage hole 52 is closed by the valve portion 22a, communication between the suction chamber 18 and the crank chamber 1a is cut off, so that the piston 13 and cylinder
Gas in the pressure stroke (blow-by gas) leaking from the gap in the bore 2a fills the crank chamber 1a, and the pressure in the crank chamber 1a increases.
Accordingly, the angle of inclination of the swash plate 8 with respect to the main shaft 3 gradually becomes smaller. Therefore, the shortest distance S between the end surface of the rotor 6 and the back surface of the swash plate 8 gradually increases. And S
When becomes more than L, the repulsive force of the spring 23 is no longer applied to the swash plate 8.

From the above, no matter what capacity control state the compressor is in when the compressor is stopped, the angular position of the swash plate 8 is regulated by the spring 23 and maintained at an angle smaller than the maximum inclination angle. Further, since the repulsive force of the spring is not applied to the swash plate 8 at this time of stopping or is extremely small, it is possible to solve the above-mentioned problems of the conventional device at the time of starting.

Although the present invention has been described above with reference to embodiments, the present invention is not limited to the above embodiments. For example, the spring means need not be limited to the coil springs shown in FIGS. It may be.

〔Effect of the invention〕

According to the variable displacement compressor of the present invention, in addition to being able to prevent a shock when the compressor is started and the resulting damage to the compressor, the swash plate has a spring repulsion when the swash plate is near its minimum inclination angle. Because power is not given,
The durability of the piston rod joint due to abnormal vibration or crank chamber pressure is also improved. Furthermore, the above effects can be achieved with a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the variable capacity compressor of the present invention, and FIG. 2 is a cross-sectional view showing another embodiment of the main part of FIG. 1. DESCRIPTION OF SYMBOLS 1... Cylinder casing, 1a... Crank chamber, 2... Cylinder block, 2a... Cylinder bore, 3... Main shaft, 6... Rotor, 8... Swash plate, 9... Rocking plate, 12... Piston rod, 1
3... Piston, 18... Suction chamber, 19... Discharge chamber, 21... Communication hole, 22... Control valve mechanism, 23
……spring.

Claims (1)

[Claims for Utility Model Registration] (1) A crank chamber, a main shaft disposed within the crank chamber, a rotor fixed to the main shaft that rotates with the rotation of the main shaft, and a rotor that is engaged with the rotor and that rotates with respect to the main shaft. a swash plate arranged in the crank chamber so as to rotate around the main shaft in an inclined plane and change an inclination angle with respect to the main shaft; and a swash plate coupled to the swash plate to swing the rotational movement of the swash plate. a rocking plate provided in the crank chamber so as to convert the movement into motion; a piston coupled to the rocking plate to perform reciprocating motion within a cylinder provided in the crank chamber; a suction chamber and a discharge chamber connected to the cylinder so as to suck fluid into the cylinder, compress it, and discharge it from the cylinder; In a variable displacement compressor equipped with a pressure adjustment means for changing the discharge volume of fluid, the swash plate is biased in a direction in which its inclination angle decreases, and after the inclination angle has decreased to a predetermined value, the swash plate is biased to a minimum inclination. A variable displacement compressor characterized in that a spring means is provided that does not apply a biasing force to the swash plate in a range up to the corner. (2) The spring means is a coil spring fitted to the main shaft between the swash plate rear surface and the rotor end surface, and its natural length is smaller than the maximum distance between the swash plate rear surface and the rotor end surface. Claim (1) characterized in that:
The variable displacement compressor described. (3) The inner diameter of the coil spring is selected to be smaller than the outer diameter of the main shaft, and when the distance between the back surface of the swash plate and the end face of the rotor exceeds a predetermined value, the end of the coil spring does not come into contact with the back surface of the swash plate. 2. The variable displacement compressor according to claim 2, wherein the variable displacement compressor is set at a position on the main shaft.